: Iridium spark plugs



capn
02-28-04, 03:43 PM
Hey all

I asked my auto tech teacher about spark plugs, and i asked him if iridium spark plugs would be benificial for a V8 like they are for a 4cylinder. and he replied "they aren't little rice rockets were talking about here" amco or w/e he said would be better than iridium plugs. is it better to run something other than iridium?

beemer2k
02-29-04, 10:32 AM
Stick with the Delcos. I've heard only horror stories about people that have put in "performance plugs" in their northstars. Problems like loss of power, mileage, accelerated (sp?) plug wear. Occasionally, you hear about a guy using Autolites and having them work fine, but... spend the extra 2 bucks a plug and get the Delcos. I just changed out my plugs and wires yesterday. Not a horrible job, but not something I would want to have to do more frequently than 100k intervals.

Aurora By Olds
03-03-04, 10:20 AM
Coming from experience.....use the Delcos. I used Bosch platinums once....total waste of money. For what its worth the Delcos are the way to go. They dont give any problems, and you wont gain any power whatsoever by having "performance" plugs in there anyway.

BeelzeBob
03-03-04, 10:45 AM
The OEM dual platinum plugs (they have been made by AC/Delphi, Nippondenso and NGK over the years...depending on the year and the supplier...) are unquestionably the best for longevity and performance.

The Bosch "platinum" plugs do not hack it. They only have platinum center electrodes. Since the direct fire ignition on the 93-99 engines fires half the plugs in "reverse polarity" it is imperative to have the DUAL platinum pads on the plugs.

The Bosch +4's seem to hurt the power on the dyno due to the extra ground electrodes shielding the spark and impeding the flame propogation in the combustion chamber.

Having said all that....the ignition on the 2000 and later Northstars is the coil at plug design with an individual coil for each plug and voltage and current scheduling done by the PCM directly. That system fires all the plugs in normal polarity with the center electrode being "positive". In that system the Iridium plugs are showing excellent performance and will probably become a production item in the future..... The iridium plugs do work well in all applications that I have seen them tested in. Just make positively sure that you have the correct heat range of plug if you start swapping/substituting plugs. The Northstar needs cold plugs to avoid preignition so be carefull of the plug heatrange if another plug is used..iridium or otherwise.

zonie77
03-03-04, 11:50 AM
The benefit of Iridium plugs seems to be an improved ability to fire under high levels of boost. Otherwise they don't have a benefit over good stock plugs.

El Dobro
03-03-04, 02:05 PM
Iridium sparkplugs are now being specified by GM for the 3.1,3.4 and 3.8 motors.

BeelzeBob
03-03-04, 03:03 PM
The benefit of Iridium plugs seems to be an improved ability to fire under high levels of boost. Otherwise they don't have a benefit over good stock plugs.


Oh yes they do.....LOL

elwesso
03-03-04, 06:23 PM
Does anyone know the p/n for the NGKs for the Northstar...

I am carrying plugs for the Q45, and Id offer them here if theyre the same number... HUGE discounts I offer!

zonie77
03-04-04, 02:04 PM
Oh yes they do.....LOL


OK Bbobynski. What's the benefit?? I havn't used them yet , just going by what I've been reading.

burekv
03-04-04, 04:56 PM
I had inquirred at a local Oreillys autoparts and they said they dont have the dual platinum plugs by ac delco. Just platinum plugs. Are the AC delco platinum plugs the same as dual platinum and how can i tell the difference between regular platinum and dual platinum. Thanks

El Dobro
03-04-04, 08:13 PM
All the AC platinum plugs that I've seen have a platinum tip on the center electrode and the ground electrode. Probably why they're called dual platinum.

BeelzeBob
03-05-04, 11:54 AM
I had inquirred at a local Oreillys autoparts and they said they dont have the dual platinum plugs by ac delco. Just platinum plugs. Are the AC delco platinum plugs the same as dual platinum and how can i tell the difference between regular platinum and dual platinum. Thanks

Not clear from your post if they are saying the AC Delco's that they have are "platinum" or if they are talking about some other sort/brand of platinum plug...??? If they are the AC Delco's then they are probably dual platinum as the only "platinum" plugs that I am aware of from AC Delco are the dual platinum....but just ask to look at one of them...the small platinum pad is welded to the center electrode and to the ground electrode adjacent to the center electrode. It is clearly visible. If there are two pads on the plug then it is a dual platinum....if not, then it isn't and don't buy it.

Some off brand plugs are called "platinum" because they come in a platinum colored box....others, like bosch, only have the center electrode made of platinum and the platinum isn't exposed...it is shielded inside the pocelean.

If all else fails get the OEM dual platinum plugs from a GM dealer or a GM parts service online.

BeelzeBob
03-05-04, 12:03 PM
Oh yes they do.....LOL


OK Bbobynski. What's the benefit?? I havn't used them yet , just going by what I've been reading.


Spark plugs work best when there is a sharp edge for the spark to initiate at. The sharper the better. That is why there are so many "fancy" plugs with a lot of edges and cuts and splines and such...to create a lot of sharp edges to initiate the spark better. Trouble is that sharp edges get dulled pretty fast inside the combustion chamber due to the heat and pressure and turbulence of the combustion. So the electrodes that start out nice and square and sharp on the edges get rounded pretty fast and the voltage requirements increase then.... Platinum is very durable and keeps the sharp edge on the platinum pads "forever" basically. Iridium center electrodes are very very hard and durable and can be made nice and small in diamter so that it creates some very sharp edges without degrading with time. This only applies when the "positive" spark initiates from the center electrode where the iridium would be. The iridium plugs only have the precious metal on the center electrode, not the ground electrode, so they don't work in the 93-99 Northstars that fired half the plugs in reverse polarity. In the 2000 and later Northstar engines the iridium plugs work very well as well as in other engines.

The main advantage of the iridium plugs is the ability to make the tiny diameter center elctrode to concentrate the electrical energy for the spark without the plug tip degrading over time.

This was accomplished to some extent (very successfully) with the dual platinum plugs with the small diameter platinum pads. bosch does this with the small diameter all platinum center electrode...but it can't stand freely without failing or overheating so it is completely enclosed in the center porcelean except for just the tip... So the iridium allows the center tip to stand freely to provide more surface exposed to the combustion chamber (even though it is so small diameter) to maximize the potential for a spark.

capn
03-05-04, 11:21 PM
Spark plugs work best when there is a sharp edge for the spark to initiate at. The sharper the better. That is why there are so many "fancy" plugs with a lot of edges and cuts and splines and such...to create a lot of sharp edges to initiate the spark better. Trouble is that sharp edges get dulled pretty fast inside the combustion chamber due to the heat and pressure and turbulence of the combustion. So the electrodes that start out nice and square and sharp on the edges get rounded pretty fast and the voltage requirements increase then.... Platinum is very durable and keeps the sharp edge on the platinum pads "forever" basically. Iridium center electrodes are very very hard and durable and can be made nice and small in diamter so that it creates some very sharp edges without degrading with time. This only applies when the "positive" spark initiates from the center electrode where the iridium would be. The iridium plugs only have the precious metal on the center electrode, not the ground electrode, so they don't work in the 93-99 Northstars that fired half the plugs in reverse polarity. In the 2000 and later Northstar engines the iridium plugs work very well as well as in other engines.

The main advantage of the iridium plugs is the ability to make the tiny diameter center elctrode to concentrate the electrical energy for the spark without the plug tip degrading over time.

This was accomplished to some extent (very successfully) with the dual platinum plugs with the small diameter platinum pads. bosch does this with the small diameter all platinum center electrode...but it can't stand freely without failing or overheating so it is completely enclosed in the center porcelean except for just the tip... So the iridium allows the center tip to stand freely to provide more surface exposed to the combustion chamber (even though it is so small diameter) to maximize the potential for a spark.
so if the iridium plug had two tips they would work better?

El Dobro
03-06-04, 12:39 PM
The AC Iridium plugs have a little pad on the ground electrode.